The present invention relates to a tube coupling consisting of a collar formed by at least two shell portions connected at their peripheral end by means of a crossing joint bolt, and comprising further a bolt lever articulated at the free peripheral end of one of the shell portions and connected to the other shell portion by means of a locking spring.
Such prior tube couplings are successfully used in practice. But in certain cases are used tubes having varying wall thicknesses. This leads to the drawback that tubes having smaller wall thicknesses than those for which the tube coupling has been designed cannot be securely clamped so that leaks may occur.
DE-GM 69 26 172 discloses a clamping ring and snap closure for tubes in which the shell portions are connected to each other at their peripheral ends by means of curved spring steel shackles. One of said spring steel shackles is articulated at the bolt lever. The pair of curved spring steel shackles permits to increase the shell portion distance so that the clamping ring also may be adapted to tubes having a larger wall thickness than the diameter for which it has been designed. Nevertheless, the connection of the shell portions by means of a curved spring steel shackle does not permit to clamp tubes having a smaller diameter than that for which the clamping ring of the state of art has been designed.
It is an object of the present invention to improve a tube coupling comprising the generic features such that with sufficient stability it may tightly clamp without risk of damage tubes of varying diamters on a mouthpiece, in particular tubes of smaller diameter than the minimum diameter for which the coupling has been designed. This means that for a varying amount of rubber between the mouthpiece and the collar the tube coupling has to automatically adjust in such a way that clamping is ensured also for smaller wall thicknesses.